<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    div {
        font-size: 40px;
        font-family: cursive;
        width: auto;
        text-align: center;
        margin: 0 auto;
        margin-top: calc(100vh * 0.5 - 100px);
    }
</style>

<body>
    <div>
        404 NOT FOUND
    </div>
</body>

</html>